Brake shoe



Dec. 22, 11931.

.F. w. sARGENT 1,837,588

BRAKE SHOE Filed Nov. 1'7, 1950 UNITED N STATES, PATE Patented Dec. 22,1931 BRAKE sELoE AND EOUNDBYGOMPANY, on WILMINeromnEL-AWAREE conforta,-

TIoN 0E DELAWARE BRAKE sinon *l 'Application mea NovemmrV 17, i930.`fs'er'i'ai ivo, 496,061,"

Y. This invention relates to brake shoesof the kind Which are provided'at the backpvvlth anN embedded reenforce plate or strip and which hasforits object to prevent thebaok from breaking after thebody ofthe/shoeVhas fracturedandto hold the parts of the body together until it is Wornout Brake shoes are made of standard curva-AV ture to -fit `standardWheels, but dueto Wear of the tread of Wheels there is often avariation.between the curvature of the face oftheshoe and the curvature of thetread of the and While these fractures may be slight at j first theydodevelop into cracks because of thevoonditions to Which brake shoes aresubjected in service. -The steel reenforceback is intended to hold theparts of the body together when it fractures or cracks .and it'usuallysuihc'es for this purpose, provided the rateof shoeavear exceeds thefatigue limit ofthe steel back which is flexed under brake `applicationat the crack in thebody andalsoby the shoe1 flappingin pits' support and`rubbing" against the Wheel When the'br'ake is in release. Continuedflexure of the back .at the crack in the body Willcause excessivefatigue of the steel 'back atthis point'if the back is held rigidly-inthe body-adjacent to thecrack. .In case of slovvfvvear of the brake shoedue to infrequent brake applications the back will break because of thisconstant flexure and the loWer'end of theshoe'will fall away before theshoelris Worn to the limitof Wear. This happens 4more oftenv on l'freight cars, Where the rate of Wear is lon7 due to light and infrequentbrakeapplications, by continued vibration and flapping of the "brokenshoe against'the Wheeh `It happens less'often on passenger cars Wherethe breaking is more seg,

vere and frequent and therate of-Wear oftheshoe is more rapid so thatthe shoe isWorn to the limit. of Wear before the steel back is destroyedby fatigue vibration. If the flex.- ure of the back is extended overanvappreciable length thereof,instead of being confinedl Y to the limitfofvvear.V

to the l'immedia-te Ilocationuof fthe crack`\,' as

Elrz WILLIAM sAEeENr, oF MAHWAH, NEWr JERSEY, AssIGNon' To THE AMEnIoANwould bethe case if the backl isheldrigidly -in the body throughout itslengthythe fatigue period of thesteel back willbefinateriallylengthened'lrand .under all indinaryl condiL tions, according-gtomylongexperience and close'ob'servation, the back `vvill holdlthe-partsY outin'servicevvithout theback breaking. l' VThe object of my inventionisft'o insure the body ofthe shoe breaking at certainpredeterminedlocations With Vreference!tofa part of the back "which is [free fromrigid con"- nection With'the bodysothat the fleXure of thefback willbefdistributed over a considerable part of the'back to prolongthewfatigue period beyond the time required Vu nderlusual conditions forWearing the body of the'jfshoe downto the limit-of Wearlf" l And vrnyinventiony also has for its'iolajeit Y tofprovide that fitti@ middleportionf'vthe ofthe bo'dy 'together until thj'e body hasv Worn backunder andadjacent?V tofthe :attaching lug shall be free'froinlrigidconnectionfvvith the body'inc-ludingfthe lug; andI further to insurethat the 'body 'Will crack transversely at orfaboutthe limits oftheloose'f portion of l y the back so thatlthe middleportion fof the bodywill be free fro'mrigid connectionfvvth the back but Willberetained'thereon by that portion ofthe body Whichcomprises theatlytachin'g 1ug, and`the`ie2iure ofthe A'back 'in service Will bedistributed throughout, the

s@ pm thereof which winpfoiongaha i fatigue period until after the``time..required for completely-Wearing oftheV `shoe V1n' theaccompanying drawings havel 1 VFig. fi is a transverse sectionalvievvonthe line 4 4 of F1g.'2,and `I Fig. 5 is a transversesection'lthrough the middleof the `attachinglug and showing a u Wider key'openingl Referring@ the amwiags', e ijsi the body Y of the,- shoe and:7 is the steel reenforce plate bask wiiiehlis embedded inthe body-alare100 back thereof. A steel lug lstrap 8 is engaged with the-back 7 and'ispartly embedded in the projections 9 of the body which form with thestrap 8 the attaching lug of the shoe. Grooves-or kerfs 10 are providedin the sides andv face of the body kat opposite Y sides of the attachinglug. These grooves are preferably parallel, or substantially par..

f allel, and they krare located at opposite sides of the attachingllugand vat such'points as may bed'etermined 'upon for thebody to crack.

Between the grooves the back is free from rigid connection with thebody. 'f The body is castvon the back and that part of the back which itisv desired shall be free Afrom rigid connection withthe bodyis-coatedwith heat I. resistingmaterial previous tothe casting operationto: prevent fusion of the cast ybodyy metal with the back in thecasting. operation., Grdinarilyithe"projections 9 completely embed thesides of the strap 8 (Fig. 4)

andproject overthe sidefedges of theback-7 Vwhichis cutaway'at llrat theattaching-lug.` Instead offcoatingthe Vback at thev middleportionmthereof to prevent it fromfusing with. thebody metal, or inaddition to the coating,I may make the key opening 112 of the attaching.lug wider asfshown `in Fig.r 5

by reducingthe sizeof the projections 9-so that'they will not overlapthe narrow middle partof the back and-this part of the backrwill befreeso that itcan llex overa considerable area. JWhile it isfdesire'd'thatthe loose vintermediate portiony of the back should extend overthatp'ortion of the shoe between the grooves-10 .vit-.isnot necessarythat there should l be absolute coincidence between the grooves `and theouter limits of the loose portion of theV back, I prefer, however, thatthe looseportion tof the back should generally andfapproximately extend`from one groove to the other and not extend materially beyond-thevgrooves, for what` I consider to.- be the best.v commercial. results,althoughf `it would notzdetractv from myinvention if the loose partofthe `back does extend beyond the grooves. In such case, if those partsof thev bodvbetween the grooves andthe ends volf-the shoe crack andtheback is loose in any. ofthe Acracked parts, the dovetail connectionbetween the'body and the back at the edges of the back l'inust be reliedupon to holdv these partsin-"place inthe shoe.l It is for this AreasonIprefer to limit the free .part of theA `back vto lapproximately thevlimits formed Ythe grooves in the body. This maybe provided for, ifoccasion requires, byy

' prolonging the freeportion of the backand locating the grooves farther.apartthan is shown `in the drawings.` V- InY-practice the body of theshoe will. `crack very early in vits use in the grooves-1() and since`the back is free from rigidconnection intermediateV part lft ofv theVbody vrbetween:y the grooves the backA willfbefree to intermediate ofthe grooves, any vibration imparted to the backl while the shoe ishang#i i ing free from the wheel yand any ilexurle of the back duetobrake applicationwill ber distributed over the entire area ofthe free'part of the back. If the back vwere held rigid in the body throughoutV.its length and the body cracked' on one or both sides of the attachedlug, theyvibrationand flexure ofV the-back would Vbe connedto the lineof the back coincident with'the crack; and .withthe vi'- b'ration soconfinedthefatigue lperiod would be comparativelyshort. .Whereas if theback is free .fromj rigid' connection with the; body. yover a`predetermined area so that' the vi vbrationell'ect-will be distributedYover this varea theffatigue period will be correspondingly prolonged. Ibelieve thatif the free .areais defined by grooves in the bodyat op fposite sides of and comparatively closeto the attaching lug it will be:sucien't to prolong the fatigue periodunder average conditions until thebody of the shoe is worn` out. The

provision of the grooves is important'tofiny in'k `surethat when' theshoe fractures the'cracks will, occur .at these predetermined locations'which, at least in a general way, define the.

limits ofthat part. of the back which is-.free

froinrigid connection with .the body and this intermediate part of thebody is heldin place by' reason "of theprojections9 rand strap- 8"which1 constitutethe attaching lug of the shoe, so that even though thisintermediate and is free from rigid connectionwith the backit will beheld from dislodgement by its anchorage on the backand will perform theservice expected of it. Y l i I have shown the' invention ina simpleadaptation with the grooves locatedclose to restricted to. this.vparticular type l.of brake shoe norvto theparticular location ofv `thegrooves.. I reserve the right t0v ymake all such changes in theform,construction and arrangement'of partsof my inventionLas-Inay -be'desirablel to satisfy different conditions'.

and within the :scope of thev following claims. Iclaim': f l

t 1. A bra-ke shoe .comprising a body and a reenforce back, saidbackbeing secured to the body but having a portion thereoffree vfrom rigidconnection -with the body, and transverse grooves on the bodycorrespond-fV ing. substantially in location witlrthe'limitsV Vof saidfreeportion 'of the back.

`2. brake shoe'comprising a Ybody anda reenforce back, said backbeingi'se'cured 'to l i part is loose from the'otherparts of the body fVthev attaching lug vbut the invention yis not izo f the back when thebody cracks on the lines of Y the grooves.

3. A brake shoe comprising a body, a reenforce back, and an attaching111g, said back being secured to the body but having that portionthereof at the attaching lug free from rigid connection with the body,and transverse grooves on the body on opposite sides of and adjacent tothe attaching 111g.

4. A brake shoe comprising a body, a reenforce back, and an attachinglug, and transverse grooves on the body at opposite sides of theattaching lug, said back being secured to the body but having thatportion thereof betWeenthe grooves free fromv rigid Y,

connection with the body. p

5. A brake shoe comprising a body, areenforce back, transverse grooveson the body at opposite sides of the attaching-lug, said back beingsecured to thebody buthaving that portion thereof between the groovesfree from rigid connection with the body, and an attaching lugcomprising projections from the body between said grooves and a lugstrap embedded in said projections and interlocked With the back at saidfree ortion.

A FITZ WILLI M SARGENT.

